Marine propulsor with inlet fluid inducer

ABSTRACT

Presented is a fluid propulsor for propelling a vehicle that incorporates a Coanda Effect Inducer (CEI), more commonly called an inlet fluid inducer in this application, in its inlet to induce fluids passing by the vehicle to turn uniformly toward a powered fluid energizing device such as a rotor of the propulsor. This concept enhances the efficiency of the rotor and the overall efficiency of the propulsor. The rotor is preferably at least primarily enclosed in a housing and the rotor may operate either fully submerged in liquid or in a partially liquid and partially gaseous environment. The CEI and the powered fluid energizing device are, in the preferred embodiment, installed in an inlet housing of the propulsor. Fluid flow directing devices may be incorporated to separate liquid from gas flowing to the rotor in some instances. The inlet fluid inducer may take the shape of a cylinder or any other flow directing shape and while more effective when rotating in the direction of fluid flow is also viable when not rotating.

CROSS REFERENCE TO OTHER APPLICATIONS

This application is a continuation-in-part to applicant's earlierapplications: Ser. No. 11/088,212 filed Mar. 18, 2005 now abandoned,Ser. No. 11/373,620 filed Mar. 10, 2006 now U.S. Pat. No. 7,422,498issued Sep. 9, 2008, and Ser. No. 11/526,958 filed Sep. 26, 2006 nowabandoned.

BACKGROUND OF THE INVENTION

Enclosed rotor propulsion system for marine craft, such as waterjets andApplicant's enclosed ventilated rotor Hydro Air Drive® (HAD) invention,are limited in the overall efficiency they can realize by the efficiencyof recovery by their water inlets of the fluid available at their waterinlets. As an example, waterjets can have very high efficiency rotors,stator vanes that straighten the discharge flow of the rotors, anddischarge nozzles. The overall efficiency of the just mentioned threeitems are in the 90% or higher area for a well-designed high power levelwaterjet.

However, the overall efficiency of a waterjet is severely limited by itsinlet's ability to recovery oncoming fluids efficiently. This is becausethe oncoming fluid flow is forced to turn into the duct that surroundsthe waterjet's rotor. As an example, a waterjet's inlet may seeefficiencies of fluid recovery of 92% over its lower half but only 54%or so over its upper half. This is because the fluid flow is separatingover the upper part of the inlet duct as it is trying to turn from theinlet toward the rotor. This is so even though the waterjet operates asan enclosed pressurized system and thereby is creating suction at itsinlet.

The HAD sees a slightly different situation in that it is not apressurized system and therefore does not create much of a suction atits inlet. The advantage of the HAD is that it only operates with thelower half of its rotor submerged so its inlet fluid does not have toturn as far as does the waterjet's. However, the lack of inlet suctionof the HAD does hamper the ability of its inlet to fully recover fluidapproaching its inlet.

What all of this means is that propulsors, such as the waterjet and theHAD, would benefit greatly by having water inducer devices at theirinlets. As a side point, it is realized that having a straight-in inletwith the inlet in-line with the rotor with no turns would provide highinlet efficiencies. Such an in-line inlet is sometimes referred to as aram inlet. The shortcomings of the ram inlet are twofold—it: 1) has highdrag due to the inlet's frontal area and 2) increases vessel draft sincethe ram inlet is normally lower than the vessel's keel. Theseshortcomings of the ram inlet are overcome by the instant-inventionwhile maintaining the ram inlet's high efficiency.

The Coanda Effect can be used for turning fluids around curved surfacesand has been known for years. This Coanda Effect can be improved by useof a rotating cylinder or other curvilinear shape placed perpendicularto or at least partially perpendicular to the fluid flow to entice thefluid to turn in the direction of rotation of the rotating surface. Theinstant invention takes advantage of these known sciences and places aCoanda Effect Inducer (CEI) at or near the entrance of the recedinginlet surface of a propulsor's inlet. The effect of the CEI is togreatly improve the recovery of fluids flowing past the propelledvehicle and of delivering such fluids to a fluid energizing device, suchas a rotor, of the propulsor. This greatly improves the overallefficiency of the propulsor and hence the performance of the vehicle.Hereinafter, the CEI is commonly called an inlet fluid inducer.

What is called the receding inlet surface hereinafter is normally theupper surface in a standard waterjet propulsor installation. Such anupper receding inlet surface may be seen in Burg, U.S. Pat. No.6,629,866, where, in that example, inlet flow directing valves 49, 51act as the preceding mentioned receding inlet surface of the propulsor.Burg's flap-like flow directing valves 49, 51 are incapable of rotationthrough 360 degrees nor do his flap-like devices 49, 51 extend below theoutlines of his hull which is the preferred embodiment of the instantinvention especially when the instant invention's fluid inlet inducer 30is fixed and not rotating. Propulsors installed in the sides of hulls,as presented in continuation-in-part Burg, U.S. Pat. No. 7,422,498, maysee the receding inlet surface and its CEI more vertically oriented. Inthe instant invention the receding inlet surface may be orientedhorizontally or at any angle to horizontal.

Willyard, U.S. Pat. No. 4,070,982, has a drive cylinder 16 disposed atthe forward end or bow of a vessel 10 that energizes oncoming water. Theenergized water then flows completely through the length of the vessel10 in a duct 15 to be discharged at the aft end of the vessel 10 therebyproviding forward thrust. Portions of Willyard's energized water may bedirected to a propeller 32 in a duct 31 positioned at the aft end ortransom of his vessel 10. However, in no case does Willyard offer a CEIthat is in powered communication with his propeller 32 except by thepassing energized water. Further, Willyard does not offer a CEI that ishoused in housings that also house the propelling rotor as does theinstant invention. The instant invention, in its preferred embodiment,has its CEI integral with its rotor housing and/or an inlet housingattached to the rotor housing which is very important in order tosimplify fabrication, installation, and maintenance. Further, Willyardhas his drive cylinder 16 disposed at the water surface at the very bowof his vessel so that it sees oncoming waves and water mixed. This iscontrary to the instant invention wherein the CEI is normally disposedat a further aft portion of the vessel's hull and normally sees onlyoncoming water.

A discussion of the instant invention and the advantages it offers ispresented in detail in the following sections.

OBJECTS OF THE INVENTION

A primary object of the invention is provide an improved propulsor forpropelling a vehicle where said propulsor accelerates fluid to producethrust and where said fluid is obtained through an inlet that intakesfluid from external to the vehicle and directs said fluid toward a fluidenergizing device wherein said inlet includes an inlet fluid inducer andwherein said inlet fluid inducer directs said fluid toward a fluidenergizing device such as a powered rotor.

A related object of the invention is that the inlet fluid inducer mayrotate.

A directly related object of the invention is that the inlet fluidinducer provide a uniformity to the energy in the fluid supplied to thefluid energizing device.

A related object of the invention is that said inlet fluid inducer beoriented more perpendicular to than parallel to a plane that includes arotational axis of the fluid energizing device.

A further object of the invention is that the inlet fluid inducer becapable of rotation in the direction of fluid flow.

Yet another object of the invention is that the inlet fluid inducerextend less than 60 percent of its maximum dimension perpendicular tofluid flow beyond an average height of a vehicle hull portion when saidvehicle hull portion is viewed proximal to, forward of, and in line withthe inlet fluid inducer.

A directly related refining object of the invention is that said inletfluid inducer extend less than 40 percent of its maximum dimensionperpendicular to fluid flow beyond an average height of a vehicle hullportion when said vehicle hull portion is viewed proximal to, forwardof, and in line with the inlet fluid inducer.

A further directly related refining object of the invention is that saidinlet fluid inducer extend less than 20 percent of its maximum dimensionperpendicular to fluid flow beyond an average height of a vehicle hullportion when said vehicle hull portion is viewed proximal to, forwardof, and in line with the inlet fluid inducer.

Yet another object of the invention is that the inlet fluid inducer mayrotate freely in the direction of fluid flow through 360 degrees ofrotation with no powering means.

Another object of the invention is that the inlet fluid inducer may bedriven by a power source that also drives the fluid energizing devicethrough 360 degrees of rotation.

A directly related object of the invention is that a drive shaft of afluid energizing device may also drive the inlet fluid inducer.

Still another object of the invention is that the fluid energizingdevice may receive primarily liquid over one portion of its rotation andprimarily gas over another portion of its rotation.

A related object of the invention is that a fluid directing device maybe disposed at least in its majority downstream of the inlet fluidinducer.

A directly related object of the invention is that the fluid directingdevice has the ability to, in at least one mode of its operation,restrict gas from passing to the fluid energizing device.

Another object of the invention is that the fluid directing device bepowered by an actuator.

Yet another object of the invention is that the inlet fluid inducer mayinclude recesses in its periphery that are capable of energizing fluidswhen the inlet fluid inducer is rotating.

A further object of the invention is that the inlet fluid inducer may bedriven with gears.

Still another object of the invention is that the fluid energizingdevice be a rotor.

Yet another object of the invention is that the fluid discharge from thefluid energizing device may be given direction by a rudder.

A further object of the invention is that the inlet fluid energizingdevice by supported by an inlet housing of the marine propulsor.

Another object of the invention is that the inlet fluid inducer and thefluid energizing device be in mechanical communication in a commonhousing or a connected housing.

It is still another object of the invention that the inlet fluid inducershould be relatively close to the fluid energing device to maximizeoverall system efficiency.

A directly related object of the invention is that a distance from anaft portion of the fluid inlet inducer to a forward portion of the fluidenergizing device be no more than six diameters of the fluid energizingdevice or rotor.

Another directly related object of the invention is that a distance froman aft portion of the fluid inlet inducer to a forward portion of thefluid energizing device be no more than four diameters of the fluidenergizing device or rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a centerline cross-sectional profile view of a prior artwaterjet propulsor.

FIG. 2 presents a cross-section, as taken through plane 2-2 of FIG. 1,that shows the general values of recovery of fluids by the inlet as seenat a plane just forward of the fluid energizing rotor that can beexpected in a commercial waterjet based on present day designs. Notethat the overall inlet efficiency, based on 92% in the lower half and54% in the upper half, comes to only about 73%.

FIG. 3 is the same centerline cross-sectional profile view as given inFIG. 1 but in this case a Coanda Effect Inducer (CEI), also called as aninlet fluid inducer herein, has been added as is a preferred embodimentof the instant invention. The direction of rotation of the inlet fluidinducer aids in directing the inlet water in a uniform manner to thefluid energizing rotor. Note that the fluid inlet inducer is shown asbeing able to rotate through a full 360 degrees of rotation which is thepreferred method of operation. However, it may also be fixed in positionwhere, while not as efficient in so doing, it will also provide theCoanda effect of turning the inlet fluid upward toward the rotor. Thefluid inlet inducer may have its rotation powered or non-powered wherein the latter case it is free-wheeling.

FIG. 4 gives a cross-section, as taken through line 4-4 of FIG. 3, thatgives the predicted values for the recovery of fluids by the inlet withthe inlet fluid inducer rotating. Note that predicted recovery values offluids entering the lower portion of the fluid energizing device is 96%and over the upper portion 90%. This results in an overall inletefficiency of 93%. The very important result is that there is about atwenty-five percent improvement in overall efficiency for a waterjetwith the inlet fluid inducer compared to one without an inlet fluidinducer.

FIG. 5 illustrates a proposed version of a inlet fluid inducer, as takenthrough plane 5-5 of FIG. 3, that shows one possible means of drivingthis cylindrical shaped inlet fluid inducer. In this particular case thedrive means consists of a drive motor with power transmitted throughgears.

FIG. 6 presents a cross-section, as taken through line 6-6 of FIG. 3,that shows a preferred flat surface forward to the inlet fluid inducer.Note that the lower surface of the inlet fluid inducer is disposed moreinto the oncoming fluid than surfaces of the hull forward of the inletfluid inducer in this example. This preferred approach insures optimumperformance of the inlet fluid inducer while adding very littleadditional drag.

FIG. 7 presents a partial profile centerline cross-section of a HAD withan instant invention inlet fluid inducer applied. There are, ideally,fluid directing means—flaps in this illustration—applied to either sideof the shaft here. In this instance, the fluid directing means areretracted to their most upward positions which allows water to flow tothe entire HAD fluid energizing rotor from top to bottom. This is thepreferred position of the fluid directing means for low vehicle speedoperation when maximum low speed thrust is desired.

FIG. 8 is the same partial profile centerline cross-section of a HAD aspresented in FIG. 7 but in this case the fluid directing means areextended downward to aid in directing fluids to only a portion of thefluid energing rotor. It is important to note also that a loweredposition of the fluid directing means allows gas to pass to the upperportion of the fluid energizing rotor. As such, the rotor is operatingonly partially submerged which has advantages compared to standardpressurized system waterjets. These advantages are discussed later inthis application.

FIG. 9 is a cross-sectional plane, as taken through 9-9 of FIG. 7, thatshows the fluid directing means in their retracted position. Note thatin this position the fluid directing means restrict the flow of gases tothe fluid energizing device which is normally a rotor with blades.

FIG. 10 is a cross-sectional plane, as taken through 10-10 of FIG. 8,that illustrates how the fluid directing means are positioned duringhigh speed vehicle operation where the fluid energizing device is onlypartially submerged.

FIG. 11 presents a cross-sectional plane, as taken through line 11-11 ofFIG. 7, that shows the fluid flow distributions just forward of thefluid energizing rotor when the fluid directing means are in theirretracted position.

FIG. 12 is a cross-sectional plane, as taken through line 12-12 of FIG.8, that illustrates fluid flow distributions just forward of the fluidenergizing rotor when the fluid directing means are in an extended highvehicle speed position. Note that there is gas above the fluid directingmeans and water below it in this instance. Inlet recovery efficienciesshould be in the 98% area over the lower half of the fluid energizingrotor in this instance.

FIG. 13 illustrates fluid flow inlet characteristics when the inletfluid inducer is not rotating. While this is very workable andconsidered part of the instant invention, performance is substantiallybetter when the inlet fluid inducer is rotating in the direction of thewater flow.

FIG. 14 shows a cross-sectional plane, as taken through line 14-14 ofFIG. 13, that illustrates water flow characteristics with the inletfluid inducer not rotating. Comparing this FIG. 13 to FIG. 12 gives someidea of the expected performance improvements to having the inlet fluidinducer rotating.

FIG. 15 illustrates flow characteristics around a non-rotating cylinderdisposed perpendicular to fluid flow. Note that the flow separatesaround the aft side of the cylinder.

FIG. 16 shows the same cylinder as that presented in FIG. 15 but withthe cylinder rotating. It is apparent that the fluid does not detach asis the case of the non-rotating cylinder of FIG. 15. This rotatingcylinder makes for a much more efficient and low drag situation than thenon-rotating cylinder of FIG. 15. Both FIGS. 15 and 16 actually showcharacteristics of the Coanda Effect since the fluid is at leastpartially attached to the curvilinear surfaces and turn inward in bothinstances.

FIG. 17 shows the same HAD unit as shown previously; however, in thiscase the inlet fluid inducer is cylindrical and rotating in an oppositedirection to travel and freestream fluid flow. This has merit in a casewhere a HAD or waterjet is not operating but the vehicle is still movingforward as would be the case of operating with their drive engine outbut with other propulsors still operating. The reason this is so is thatthe forward direction of rotation of the inlet fluid inducer directsoncoming fluids away form the HAD's inlet thereby reducing drag forcesthat would occur with fluid entering a non-operating unit.

FIG. 18 presents a centerline profile cross-section plane that shows analternate method of driving an inlet fluid inducer. In this case theinlet fluid inducer is directly driven by a main drive shaft of apropulsor. Also, this figure shows how an inlet fluid inducer could workwhen operating in reverse as is the inlet fluid inducer here. Runningthe inlet fluid inducer in reverse, either powered or non-powered, alongwith reverse operation of the rotor results in enhanced reverse thrust.

FIG. 19 presents a cross-section plane, as taken through 19-19 of FIG.18.

FIG. 20 is a cross-section plane, as taken through 20-20 of FIG. 18. Theinlet fluid inducer illustrated here is in the form of truncated coneseither side of a gear drive track. Realize that the inlet fluid inducercan take many shapes to accommodate different hull shapes, inletdesigns, and the like.

FIG. 21 is another cross-section plane, as taken through 21-21 of FIG.18, that shows an optional elliptical, as seen in this cross-section,shaped inlet fluid inducer.

FIG. 22 shows yet another version of an inlet fluid inducer that in thiscase is made up of two separate parts.

FIG. 23 is a partial centerline cross-section plane with a variation ofan inlet fluid inducer that incorporates pumping recesses to enhancepumping or fluid accelerating abilities of the inlet fluid inducer.

FIG. 24 is a cross-section plane, as taken through 24-24 of FIG. 23,that shows the preferred shape and workings of the inlet fluid inducervariation of FIG. 23.

DETAILED DESCRIPTION

FIG. 1 shows a centerline cross-sectional profile view of a prior artwaterjet propulsor as it is propelling a vehicle 39 forward at highspeed. Note that high speed is defined herein as being forward speeds of15 knots or more and low speeds as speeds of less than 15 knots. Shownalso are the shaft 31, fluid energizing device which in this case is arotor 42, stator including flow straightening stator vanes 40, anddischarge nozzle 41. Other items of interest include inlet housing 34,vehicle hull 39, waterline 45, waterflow arrows 37, turbulent water flowarrows 50, and thrust arrow 51. The power source is not shown tosimplify the drawings. Note that the turbulent water flow arrows 37indicate that the water flow is separating over the upper surface of theinlet housing 34.

FIG. 2 presents a cross-section, as taken through plane 2-2 of FIG. 1,that shows the general values of recovery of energy available at theinlet 55 in a plane just forward of the rotor 35 as can be expected in alarge commercial waterjet to today's technology. The overall inletefficiency can be approximately determined from the inlet pressureislands 47. Note that the approximate overall inlet efficiency, based on92% in the lower half and 54% in the upper half, comes to only 73%.

FIG. 3 is the same centerline cross-sectional profile view as given inFIG. 1 but in this case a Coanda Effect Inducer (CEI), more commonlycalled an inlet fluid inducer 30 herein, has been added as is one formof a preferred embodiment of the instant invention marine propulsor 53.The direction of rotation, as shown by rotation arrow 49, of this inletfluid inducer 30 aids in directing and adding energy to the recoveredincoming fluid as it is directed to the fluid energizing device such asrotor 42. Note that the fluid inlet inducer 30 is shown as being able torotate through a full 360 degrees of rotation which is the preferredmethod of operation. However, it may also be fixed in position where,while not as efficient in so doing, it will also provide the Coandaeffect of turning the inlet fluid upward toward the rotor. The fluidinlet inducer 30 may have its rotation powered, the most efficient meansfor turning the inlet fluid upward toward the rotor 42, or non-poweredwhere in the latter case it is free-wheeling.

The inlet fluid inducer 30 should be relatively close to the fluidenerging device or rotor 42 for maximum overall system efficiency. Adistance from an aft portion of the fluid inlet inducer 30 to a forwardportion of the fluid energizing device 42 of no more than six diametersof the fluid energizing device or rotor 42 is desired with values ofless than four diameters preferred. Further, in this preferredembodiment of the instant invention, the inlet fluid inducer 30 issupported by the inlet housing 34. The two items presented in thisparagraph are very important as they make for the best manufacture,installation, maintenance, and efficiency.

The dimension A given in FIG. 3 shows that the inlet fluid inducer 30can extend below the average depth of the hull portion 39 forward of theinlet fluid inducer 30. Having the inlet fluid inducer 30 on averagelower than the hull portion 39 forward of it allows the inlet fluidinducer 30 to operate more efficiently and in cleaner water. This isdone with very little addition to the drag of the inlet as will bediscussed later in the descriptions of FIGS. 15 and 16.

In FIG. 3 and subsequent figures in this application, dimension A isbest defined as a percentage of the diameter of the inlet fluid inducer30 and may extend to as much as 60 percent or more of the diameter ofthe inlet fluid inducer 30 and offer advantage in efficiency of recoveryof fluids external to the inlet and still add little drag to thevehicle. For purposes of this application, the amount that the inletfluid inducer 30 can extend beyond the average height of a hull portion39 forward of the inlet fluid inducer 30 is either not specified ordefined as less than 60% of inlet fluid inducer 30 diameter, less than40% of inlet fluid inducer 30 diameter, or less than 20% of inlet fluidinducer 30 diameter. It is to be noted that the term diameter used herecan actually be the maximum dimension of the inlet fluid inducer 30 thatis perpendicular to fluid flow as could be the case for shapes otherthan cylindrical.

Each of these extensions, relative to the hull portions, have advantagesand disadvantages. For example, in the case of a Surface Effect Ship(SES) such as applicant's SeaCoaster® that is supported by pressurizedgas cushions with the propulsor inlets disposed at least primarily aftof the gas cushions it is best to have the inlet fluid inducer 30 extendbeyond the hull portion in front of it as far as possible. This isbecause the gas cushions aerate the water and there may also be a layerof gas between the hull 39 and the water surface when it reaches thepropulsor's water inlet. Having the inlet fluid inducer 30 extendoutward beyond the hull means that its outward portions can work inrelatively clean gas free liquid. Contrarily, it is desirable to havethe inlet fluid inducer 30 not so far extended for a very high-speedcraft.

Large displacement hulls may find extension of the inlet fluid inducer30 to work best when at low values also. This is because of the boundarylayer associated with large displacement hulls and the desire to take inwater to the propulsor from close to the hull where it has already beenbrought up to near ship speed. The advantage of the instant invention insuch a displacement hull application is that the propulsor gets an addedthrust advantage from taking in the ship's accelerated boundary layerrather than quiescent water in outer reaches of the boundary layer. Itis further to be noted that the instant invention may be disposed sothat it is actually has all or part of its inlet higher than its fluidenergizing rotor as would be the case when operating on the upper orside surfaces of hydrofoil, submarine, or other submerged or partiallysubmerged vehicle.

FIG. 4 presents a cross-section, as taken through line 4-4 of FIG. 3,that gives the predicted values for the recovery of the inlet fluid withthe inlet fluid inducer 30 rotating as shown. Note that the expectedrecovery over the lower portion of the fluid energizing rotor is 96% andover the upper portion 90%. This results in an overall inlet efficiencyof 93%. The net result is about a twenty-seven percent improvement inoverall waterjet efficiency for a waterjet with the inlet fluid inducercompared to one without.

FIG. 5 illustrates a proposed version of an inlet fluid inducer 30, astaken through plane 5-5 of FIG. 3, that shows one possible means ofdriving this cylindrical shaped inlet fluid inducer 30. In this case thedrive means consists of a drive motor 43 with power transmitted througha set of right angle gears 44. The drive motor 43 may be drivenelectrically, hydraulically, or by other means.

FIG. 6 presents a cross-section, as taken through line 6-6 of FIG. 3,that shows a preferred flat hull 39 surface forward to the inlet fluidinducer 30. Note that the lower surface of the inlet fluid inducer 30 isdisposed more into the freestream than surfaces forward of the inletfluid inducer 30 as shown here. This preferred approach shown hereinsures optimum performance of the inlet fluid inducer 30 while addingvery little additional drag. However, it is to be realized that, whilethe arrangement shown is preferred, that the instant invention's inletfluid inducer 30 can actually be flush with the hull 30 surfaces or evenrecessed from them and such arrangements are considered within thespirit and scope of the instant invention.

FIG. 7 presents a partial profile centerline cross-section of a HydroAir Drive (HAD) 54 with an instant invention inlet fluid inducer 30applied. There are, ideally, fluid directing means 33—flaps in thisillustration—applied. These flaps 33 are to either side of the shaft 31in this preferred arrangement of the instant invention. In this FIG. 7,the fluid directing means 33 are retracted to their most upwardpositions with power supplied by actuators 32 which allows water to flowto the entire HAD fluid energizing rotor 35 from top to bottom. This isthe preferred position of the fluid directing means 33 for low vehiclespeed operation to provide maximum low speed thrust.

Another item of note in FIG. 7 is the optional use of low cost and lowmaintenance labyrinth seals 52 to restrict water from flowing freelyaround the inlet fluid inducer 30. While the fluid inlet 55 is shownbelow the fluid energizing rotor 35 here it is to be realized that itcan be fully or partially to the side of or even above the fluidenerging rotor 35 as a particular installation may dictate. An optionalrudder 36 that provides steering in forward and in reverse is alsoshown.

FIG. 8 is the same partial profile centerline cross-section of a HAD 54as presented in FIG. 7 but in this case the fluid directing means 33 areextended downward to aid in directing liquid flow to only a portion ofthe fluid energizing rotor 35. It is important to note also that alowered position of the fluid directing means 33 allows gas to pass tothe upper portion of the rotor 42 through gas passageways 57 as isindicated by gas flow arrows 38. As such, the fluid energizing rotor 35is operating only partially submerged which has advantages compared tostandard pressurized system waterjets. Two of these advantages are: 1)The HAD rotor is not subject to cavitation damage since it is aeratedand 2) Ingestion of aerated water by the HAD does not result in a severeperformance decay it does in the case of a standard pressurized systemwaterjet.

FIG. 9 is a cross-sectional plane, as taken through 9-9 of FIG. 7, thatshows the fluid directing means 33 in their retracted position. Notethat gas flow is restricted from entering the duct and from reaching thefluid energizing rotor 35 since it is blocked from doing so by the fluiddirecting means 33.

FIG. 10 is a cross-sectional plane, as taken through 10-10 of FIG. 8,that illustrates how the fluid directing means 33 are positioned duringhigh speed vehicle operation where the fluid energizing rotor 35 is onlypartially submerged. Note the gas flow arrows 38 that show that gas ispassing through in this arrangement. Waterlines 45 either side of theinstant invention propulsor 54 are also shown.

FIG. 11 presents a cross-sectional plane, as taken through line 11-11 ofFIG. 7, that shows the fluid flow distributions, as indicated by fluidenergy islands 47, just forward of the fluid energizing rotor when thefluid directing means are in their retracted position.

FIG. 12 is a cross-sectional plane, as taken through line 12-12 of FIG.8, that illustrates fluid flow distributions, as indicated by fluidenergy islands 47, just forward of the fluid energizing rotor when thefluid directing means are in an extended high vehicle speed position.Note that there is gas above the fluid directing means and liquid belowit in this instance. Inlet recovery efficiencies should be in the 98%area over the lower half of the fluid energizing rotor in this instancewhere the inlet fluid inducer is rotating and adding energy anddirection to the incoming fluids.

FIG. 13 illustrates fluid flow inlet characteristics when the inletfluid inducer is not rotating. While this is very workable andconsidered part of the instant invention, performance is substantiallybetter when the inlet fluid inducer is rotating in the direction of thewater flow. Expected inlet recoveries should be in about the 80% area inthis case with the inlet fluid inducer not rotating. Note also that thewaterline 45 is lower than in the case where the inlet fluid inducer isrotating as seen in FIG. 12 so the fluid energizing rotor would mostlikely not be receiving as much liquid as the fluid energizing rotor ofFIG. 12.

FIG. 14 shows a cross-sectional plane, as taken through line 14-14 ofFIG. 13, that illustrates liquid flow characteristics with the inletfluid inducer not rotating. Note the lower waterline 45 here than inFIG. 12. Also, the expected recovery is 80% while it is 98% in FIG. 12where the inlet fluid inducer is rotating in the direction of fluidflow.

FIG. 15 illustrates flow characteristics around a non-rotating cylinder48 disposed perpendicular to ideal fluid flow. Note that the flow,indicated by turbulent flow lines 50, separates around the aft side ofthe cylinder 48.

FIG. 16 shows the same cylinder 48 as that presented in FIG. 15 but withthe cylinder 48 rotating in the direction of flow as is indicated byrotation arrow 49. It is apparent that the fluid does not detach as isthe case of the cylinder 48 that is not rotating of FIG. 15. Thisrotating cylinder 48 makes for a much more efficient and low dragsituation than the cylinder 48 that is not rotating of FIG. 15. BothFIGS. 15 and 16 actually show characteristics of the Coanda Effect sincethe fluid is at least partially attached to the curvilinear surfaces onthe aft side of the cylinder 48 and turn inward.

FIG. 17 shows the same HAD 54 as shown previously; however, in this casethe inlet fluid inducer 30 is rotating in an opposite direction totravel and external fluid flow. This has merit in a case where a HAD orwaterjet is not operating but the vehicle is still moving forward sincethis forward direction of rotation of the inlet fluid inducer 30prevents water from entering the HAD's inlet 55 thereby reducing drag.

FIG. 18 presents a centerline profile cross-section plane that shows analternate method of driving an inlet fluid inducer 30. In this case theinlet fluid inducer 30 is directly driven by a main drive shaft 31 ofthe propulsor. Also, this figure shows how an inlet fluid inducer 30could work when operating in reverse as is the inlet fluid inducer 30here. Running the inlet fluid inducer 30 in reverse along with reverseoperation of the fluid energizing rotor results 35 in enhanced reversethrust.

FIG. 19 presents a cross-section plane, as taken through 19-19 of FIG.18. Note that the fluid flow directing means 33 are retracted here.

FIG. 20 is a cross-section plane, as taken through 20-20 of FIG. 18. Theinlet fluid inducer 30 illustrated here is in the form of truncatedcones either side of a gear track 46. Realize that the inlet fluidinducer 30 can take many shapes to accommodate different hull shapes,inlet designs, and the like.

FIG. 21 is another cross-section plane, as taken through 21-21 of FIG.18, that shows an optional elliptical shaped inlet fluid inducer 30.

FIG. 22 shows yet another version of an inlet fluid inducer 30 that inthis case is made up of two parts.

FIG. 23 is a partial centerline cross-section plane with a variation ofan inlet fluid inducer that incorporates pumping recesses 56 to enhancepumping or fluid accelerating abilities of the inlet fluid inducer 30.Note that other manners of shape and of possible recesses in the inletfluid inducer 30 are considered within the spirit and scope of theinstant invention.

FIG. 24 is a cross-section plane, as taken through 24-24 of FIG. 23,that shows a preferred shape and workings of the inlet fluid inducer 30variation of FIG. 23.

While the invention has been described in connection with a preferredand several alternative embodiments, it will be understood that there isno intention to thereby limit the invention. On the contrary, there isintended to be covered all alternatives, modifications and equivalentsas may be included within the spirit and scope of the invention asdefined by the appended claims, which are the sole definition of theinvention.

1. In an improved propulsor for propelling a marine vehicle wherein saidpropulsor accelerates fluid to produce thrust and wherein said fluid isobtained through an inlet that intakes fluid from external to the marinevehicle and directs said fluid toward a powered fluid energizing deviceof said propulsor, the improvement comprising: an inlet fluid inducerwherein said inlet fluid inducer is capable of three hundred sixtydegrees of rotation to thereby energize and direct said fluid toward thepowered fluid energizing device and wherein a power source that suppliespower to said powered fluid energizing device of said propulsor alsosupplies power to said inlet fluid inducer and wherein said inlet fluidinducer is driven by drive means in mechanical communication with adrive shaft of the powered fluid energizing device of said propulsor. 2.The improved propulsor of claim 1 wherein said drive means includesgears.
 3. The improved propulsor of claim 1 wherein a distance from anaft portion of said inlet fluid inducer to a forward portion of thefluid energizing device is no more than six diameters of the fluidenergizing device.
 4. The improved propulsor of claim 1 wherein adistance from an aft portion of said inlet fluid inducer to a forwardportion of the fluid energizing device is no more than four diameters ofthe fluid energizing device.
 5. The improved propulsor of claim 1wherein said inlet fluid inducer and the fluid energizing device are inmechanical communication by means of one or more housings of thepropulsor.
 6. The improved propulsor of claim 1 wherein said inlet fluidinducer extends less than 40 percent of its maximum dimensionperpendicular to fluid flow beyond an average height of a vehicle hullportion when said vehicle hull portion is viewed proximal to, forwardof, and in line with the inlet fluid inducer.
 7. The improved propulsorof claim 1 wherein said powered fluid energizing device receivesprimarily liquid over one portion of its rotation and primarily gas overanother portion of its rotation.
 8. The improved propulsor of claim 7wherein a fluid directing device is disposed, at least in its majority,downstream of the inlet fluid inducer and upstream of the fluidenergizing device.
 9. The improved propulsor of claim 1 wherein saidinlet fluid inducer includes recesses in its periphery that are capableof energizing fluids when the inlet fluid inducer is rotating.
 10. Theimproved propulsor of claim 1 wherein the inlet fluid inlet inducer iscapable of free wheeling rotation in a direction of fluid flow when saidinlet fluid inducer is not powered.
 11. In an improved propulsor forpropelling a marine vehicle wherein said propulsor accelerates fluid toproduce thrust and wherein said fluid is obtained through an inlet thatintakes the fluid from external to the marine vehicle and directs saidfluid toward a powered fluid energizing device of said propulsor, theimprovement comprising: an inlet fluid inducer wherein said inlet fluidinducer is capable of three hundred sixty degrees of rotation to therebyenergize and direct said fluid toward the powered fluid energizingdevice and wherein a distance from an aft portion of said inlet fluidinducer to a forward portion of the fluid energizing device is no morethan six diameters of the fluid energizing device.
 12. The improvedpropulsor of claim 11 wherein a distance from an aft portion of saidinlet fluid inducer to a forward portion of the fluid energizing deviceis no more than four diameters of the fluid energizing device.
 13. Theimproved propulsor of claim 11 wherein said inlet fluid inducer and thefluid energizing device are in mechanical communication by means of oneor more housings of the propulsor.
 14. The improved propulsor of claim11 wherein said inlet fluid inducer extends less than 40 percent of itsof its maximum dimension perpendicular to fluid flow beyond an averageheight of a vehicle hull portion when said vehicle hull portion isviewed proximal to, forward of, and in line with the inlet fluidinducer.
 15. The improved propulsor of claim 11 wherein said inlet fluidinducer is driven by drive means in mechanical communication with adrive shaft of the powered fluid energizing device of said propulsor.16. The improved propulsor of claim 11 wherein said powered fluidenergizing device receives primarily liquid over one portion of itsrotation and primarily gas over another portion of its rotation.
 17. Theimproved propulsor of claim 11 wherein a fluid directing device isdisposed, at least in its majority, downstream of the inlet fluidinducer and upstream of the fluid energizing device.
 18. The improvedpropulsor of claim 11 wherein said inlet fluid inducer includes recessesin its periphery that are capable of energizing fluids when the inletfluid inducer is rotating.
 19. The improved propulsor of claim 11wherein the inlet fluid inlet inducer is capable of free wheelingrotation in a direction of fluid flow when said inlet fluid inducer isnot powered.
 20. The improved propulsor of claim 11 wherein a distancefrom an aft portion of said inlet fluid inducer to a forward portion ofthe fluid energizing device is no more than six diameters of the fluidenergizing device.
 21. The improved propulsor of claim 11 wherein adistance from an aft portion of said inlet fluid inducer to a forwardportion of the fluid energizing device is no more than four diameters ofthe fluid energizing device.
 22. In an improved propulsor for propellinga marine vehicle wherein said propulsor accelerates fluid to producethrust and wherein said fluid is obtained through an inlet that intakesthe fluid from external to the marine vehicle and directs said fluidtoward a powered fluid energizing device of said propulsor, theimprovement comprising: an inlet fluid inducer wherein said inlet fluidinducer is capable of three hundred sixty degrees of rotation toenergize and direct said fluid toward the powered fluid energizingdevice and wherein said inlet fluid inducer and the fluid energizingdevice are in mechanical communication by means of one or more housingsof the propulsor.
 23. The improved propulsor of claim 22 wherein adistance from an aft portion of said inlet fluid inducer to a forwardportion of the fluid energizing device is no more than six diameters ofthe fluid energizing device.
 24. The improved propulsor of claim 22wherein a distance from an aft portion of said inlet fluid inducer to aforward portion of the fluid energizing device is no more than fourdiameters of the fluid energizing device.
 25. The improved propulsor ofclaim 22 wherein said inlet fluid inducer is driven by drive means inmechanical communication with a drive shaft of the powered fluidenergizing device of said propulsor.
 26. The improved propulsor of claim22 wherein said fluid energizing device receives primarily liquid overone portion of its rotation and primarily gas over another portion ofits rotation.
 27. The improved propulsor of claim 22 wherein a fluiddirecting device is disposed at least in its majority downstream of theinlet fluid inducer.